Optical disks and magneto-optic disks (hereinafter will be referred to simply as disks) have recently gained wide popularity as information recording mediums, and created demands for a disk loading device capable of storing a plurality of disks at one time to realize easy handling of a plurality of disks. Accordingly, various types of disk loading devices have been invented.
However, those types of disk loading devices do not allow the user to load, unload or replace a disk while another disk is in reproduction or recording. Therefore, the user must stop the reproduction or recording temporarily or wait until the reproduction or recording is finished, before he can load, unload or replace that disk. In addition, such disk loading devices tend to be large so as to allow storage of a plurality of disks. Accordingly, a new type of disk loading device is in demand to solve these inconveniences.
Japanese Laid-Open Patent Application No. 7-282520/1995 (Tokukaihei 7-282520) discloses a disk reproducing device which meets the requirements. The disk reproducing device includes a pair of a main tray and a subtray. The subtray moves a disk between a disk replacement position outside the housing and a reproduction position. The subtray is held by the main tray so as to be movable between the disk replacement position and a standby position inside the housing.
An individual rack is provided to the subtray and the main tray, and one pinion engages one of two racks. Specifically, the pinion is elevated and lowered along the rotation axis thereof by pinion moving means that includes a pinion elevating and lowering cam, and shifts to a position where it engages one of the two racks. The pinion elevating and lowering cam is a cylinder with a plurality of cam surfaces in accordance with the position of the pinion.
The disk reproducing device includes a fluctuation gear and a reproducing section elevating and lowering cam for elevating and lowering a reproducing mechanism. The reproducing section elevating and lowering cam is a cylinder cam with a plurality of cam surfaces in accordance with the position of the reproducing section, for elevating and lowering the reproducing section that includes a turn table, an optical pickup unit, etc. The fluctuation gear fluctuates depending upon the rotation direction of the motor and thereby rotates either the pinion elevating and lowering cam or the reproducing section elevating and lowering cam. Two kinds of cams can be driven with a single motor in this manner.
However, in the disk reproducing device, the pinion is driven upward and downward so as to engage the rack of one of the trays during the reciprocal movement of the main tray between the disk replacement position and the standby position and the reciprocal movement of the subtray between the standby position and the reproduction position. This requires both the subtray and the main tray to be provided with an individual rack, adding to the costs for the disk reproducing device.
A method of removing such inconvenience is to remove the subtray and change the configuration of the disk reproducing device so that the disk can be moved only by the main tray. This configuration, however, requires a portion of the main tray on which the disk is mounted to be movable between the disk replacement position and the reproduction position, and therefore that the main tray travel a longer distance than that in the previous configuration including the subtray. Consequently, the disk reproducing device needs a larger housing to allow for that travel distance for the main tray.
When the subtray and the main tray are both in the standby positions, one of those trays, not held by the pinion, might change its position on its own, and is disposed relative to the rack of the other tray. Consequently, when the pinion is elevated or lowered so as to move the disposed tray again, the rack of the tray and the pinion might possibly not engage each other.
Displacement of the rack is eliminated by slightly moving the pinion and thus correcting the engagement position of the pinion with the rack. According to this method, the pinion is slightly moved until the rack is back in the right engagement position, and then driven at a speed predetermined to move the tray. Therefore, the method requires a device for detecting that the rack has reached its right engagement position, and may complicate the controls of the tray moving means for driving the pinion.
Relative displacement between the racks can also be eliminated by moving the pinion as much as the racks have been disposed. According to the method, the pinion is horizontally moved until the pinion is in the right position to engage the disposed rack. Therefore, the method requires a mechanism for moving the pinion relative to the subtray or the main tray.
With the disk reproducing device, a pinion elevating and lowering cam and a reproducing section elevating and lowering cam are provided separately, one of the cams is selectively driven by a single motor. The drive mechanism turns the cams in fixed directions using the fluctuation gears engaging one of gears provided to the cams. Thus, selections from a plurality of pairs of trays (pairs of a subtray and a main tray) and upward and downward movements of the reproducing section in accordance with the pair of trays (hereinafter, will be inclusively referred to as reproduction preparatory movement) are executed in a predetermined sequence.
Therefore, after the reproduction preparatory movement for a disk on the top (bottom) shelf, the operation proceeds to a reproduction preparatory movement for a disk on a lower (upper) shelf. However, after the reproduction preparatory movements for the other shelves than the top and bottom shelves, the operation proceeds either to an upper shelf or to a lower shelf. Therefore, the cams need two cam surfaces of the same height on both sides of the highest cam surface and the lowest cam surface. In addition, a device may possibly be needed for detecting the position of the pinion and that of the reproducing section, and complicate the controls of the tray moving means.
With the disk reproducing device, while the main tray is moving between the standby position and the disk replacement position, the pinion engages only the rack of the main tray, not the rack of the subtray. Therefore, the subtray may possibly be moved and disposed relative to the main tray, while the main tray is being moved.
The pinion, when in the standby and reproduction positions and between those positions, does not engage the rack of the main tray, and is only held by the housing. An electrically driven holding mechanism is needed to hold the pinion, and the main tray needs to be so thick and strong to be held by the holding mechanism. The holding mechanism needs to release the main tray when the rack of the main tray engages the pinion. If the main tray is not released at the right timing, the main tray cannot shift from the holding state to the moving state.
With the disk reproducing device, in order that the reproducing section including the turn table and an optical pickup unit do not contact the moving disk during the turning movement of the reproducing section elevating and lowering cam, the reproducing section retreats downward relative to the subtray moving to the reproduction position, and when the subtray reaches the reproduction position the disk is scooped with the reproducing section moved upward. Then, a damper provided to the reproducing section so as to be turned up and down is lowered to secure the disk to the turn table. Therefore, a mechanism for vertically turning the damper is provided for that purpose only. Besides, since the damper is lowered obliquely, the disk cannot be firmly secured to the turn table in some cases.
The disk reproducing device requires a detecting device for detecting the disk replacement position, the standby position, and the reproduction position, a detecting device for detecting the position of the pinion (the rotation position of the pinion elevating and lowering cam), and a detecting device for detecting the position of the reproducing section (the rotation position of the reproducing section elevating and lowering cam), each detecting device being provided separately from the others. Moreover, in some cases, a detecting device for detecting the securing of the disk by the damper and the release of the securing needs to be provided. Therefore, the controls of the disk loading is carried out on the basis of the three or four kinds of detection signals from the detecting devices, which complicates the controls.